Identify the ligand with the highest field strength among the following.

Ammonia forms the complex $[Cu(NH_3)_4]^{2+}$ with copper ions in alkaline solution but not in acidic solution. The reason for this is

$X$ is the number of electrons in $t_{2g}$ orbitals of the most stable complex ion among $[Fe(NH_3)_6]^{3+}$,$[Fe(Cl)_6]^{3-}$,$[Fe(C_2O_4)_3]^{3-}$ and $[Fe(H_2O)_6]^{3+}$. The nature of the oxide of vanadium of the type $V_2O_X$ is:

$[Cu(CN)_4]^{2-}$ is colourless as it absorbs light in

Which equilibrium can be described as an acid-base reaction using the Lewis acid-base definition but not using the Bronsted-Lowry definition?

Arrange the following complexes in the increasing order of conductivity of their solution:
$[Co(NH_{3})_{3}Cl_{3}], [Co(NH_{3})_{4}Cl_{2}]Cl, [Co(NH_{3})_{6}]Cl_{3}, [Cr(NH_{3})_{5}Cl]Cl_{2}$